scholarly journals Skyrmion ratchet propagation: utilizing the skyrmion Hall effect in AC racetrack storage devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Börge Göbel ◽  
Ingrid Mertig
Keyword(s):  
Hall Effect ◽  
Soft Or ◽  
Directed Motion ◽  
Ratchet Mechanism ◽  
Storage Devices ◽  
Unique Effect ◽  
Magnetic Skyrmions ◽  
Memory Applications ◽  
Classical Particles ◽  
Transverse Deflection

AbstractMagnetic skyrmions are whirl-like nano-objects with topological protection. When driven by direct currents, skyrmions move but experience a transverse deflection. This so-called skyrmion Hall effect is often regarded a drawback for memory applications. Herein, we show that this unique effect can also be favorable for spintronic applications: We show that in a racetrack with a broken inversion symmetry, the skyrmion Hall effect allows to translate an alternating current into a directed motion along the track, like in a ratchet. We analyze several modes of the ratchet mechanism and show that it is unique for topological magnetic whirls. We elaborate on the fundamental differences compared to the motion of topologically trivial magnetic objects, as well as classical particles driven by periodic forces. Depending on the exact racetrack geometry, the ratchet mechanism can be soft or strict. In the latter case, the skyrmion propagates close to the efficiency maximum.

scholarly journals Visualizing the strongly reshaped skyrmion Hall effect in multilayer wire devices

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anthony K. C. Tan ◽  
Pin Ho ◽  
James Lourembam ◽  
Lisen Huang ◽  
Hang Khume Tan ◽  
...  
Keyword(s):  
Hall Effect ◽  
Topological Charge ◽  
Size Dependence ◽  
Particle Model ◽  
Model Simulations ◽  
Generation Computing ◽  
Magnetic Skyrmions ◽  
Transverse Deflection ◽  
Robust Framework ◽  
Geometric Effects

AbstractMagnetic skyrmions are nanoscale spin textures touted as next-generation computing elements. When subjected to lateral currents, skyrmions move at considerable speeds. Their topological charge results in an additional transverse deflection known as the skyrmion Hall effect (SkHE). While promising, their dynamic phenomenology with current, skyrmion size, geometric effects and disorder remain to be established. Here we report on the ensemble dynamics of individual skyrmions forming dense arrays in Pt/Co/MgO wires by examining over 20,000 instances of motion across currents and fields. The skyrmion speed reaches 24 m/s in the plastic flow regime and is surprisingly robust to positional and size variations. Meanwhile, the SkHE saturates at ∼22∘, is substantially reshaped by the wire edge, and crucially increases weakly with skyrmion size. Particle model simulations suggest that the SkHE size dependence — contrary to analytical predictions — arises from the interplay of intrinsic and pinning-driven effects. These results establish a robust framework to harness SkHE and achieve high-throughput skyrmion motion in wire devices.

scholarly journals Coexistence of distinct skyrmion phases observed in hybrid ferromagnetic/ferrimagnetic multilayers

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrada-Oana Mandru ◽  
Oğuz Yıldırım ◽  
Riccardo Tomasello ◽  
Paul Heistracher ◽  
Marcos Penedo ◽  
...  
Keyword(s):  
Hall Effect ◽  
Low Temperatures ◽  
Room Temperature ◽  
Multilayer System ◽  
Efficient Storage ◽  
A Chain ◽  
Magnetic Skyrmions ◽  
Memory Applications

AbstractMaterials hosting magnetic skyrmions at room temperature could enable compact and energetically-efficient storage such as racetrack memories, where information is coded by the presence/absence of skyrmions forming a moving chain through the device. The skyrmion Hall effect leading to their annihilation at the racetrack edges can be suppressed, for example, by antiferromagnetically-coupled skyrmions. However, avoiding modifications of the inter-skyrmion distances remains challenging. As a solution, a chain of bits could also be encoded by two different solitons, such as a skyrmion and a chiral bobber, with the limitation that it has solely been realized in B20-type materials at low temperatures. Here, we demonstrate that a hybrid ferro/ferri/ferromagnetic multilayer system can host two distinct skyrmion phases at room temperature, namely tubular and partial skyrmions. Furthermore, the tubular skyrmion can be converted into a partial skyrmion. Such systems may serve as a platform for designing memory applications using distinct skyrmion types.

scholarly journals Emulating spin transport with nonlinear optics, from high-order skyrmions to the topological Hall effect

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Aviv Karnieli ◽  
Shai Tsesses ◽  
Guy Bartal ◽  
Ady Arie
Keyword(s):  
Photonic Crystals ◽  
Hall Effect ◽  
Optical System ◽  
Crystal Engineering ◽  
Spin Transport ◽  
Research Effort ◽  
Nonlinear Photonic Crystals ◽  
Topological Hall Effect ◽  
Magnetic Skyrmions ◽  
Quantum Optical

AbstractExploring material magnetization led to countless fundamental discoveries and applications, culminating in the field of spintronics. Recently, research effort in this field focused on magnetic skyrmions – topologically robust chiral magnetization textures, capable of storing information and routing spin currents via the topological Hall effect. In this article, we propose an optical system emulating any 2D spin transport phenomena with unprecedented controllability, by employing three-wave mixing in 3D nonlinear photonic crystals. Precise photonic crystal engineering, as well as active all-optical control, enable the realization of effective magnetization textures beyond the limits of thermodynamic stability in current materials. As a proof-of-concept, we theoretically design skyrmionic nonlinear photonic crystals with arbitrary topologies and propose an optical system exhibiting the topological Hall effect. Our work paves the way towards quantum spintronics simulations and novel optoelectronic applications inspired by spintronics, for both classical and quantum optical information processing.

Magnetic skyrmions without the skyrmion Hall effect in a magnetic nanotrack with perpendicular anisotropy

Nanoscale ◽  
2017 ◽  
Vol 9 (29) ◽  
pp. 10212-10218 ◽  
Author(s):  
Yue Zhang ◽  
Shijiang Luo ◽  
Baiqian Yan ◽  
Jun Ou-Yang ◽  
Xiaofei Yang ◽  
...  
Keyword(s):  
Hall Effect ◽  
Perpendicular Anisotropy ◽  
Magnetic Skyrmions

Anisotropy engineering was exploited to prevent the skyrmion Hall effect that is bad for application in memory.

scholarly journals Interface-driven topological Hall effect in SrRuO3-SrIrO3 bilayer

2016 ◽  
Vol 2 (7) ◽  
pp. e1600304 ◽  
Author(s):  
Jobu Matsuno ◽  
Naoki Ogawa ◽  
Kenji Yasuda ◽  
Fumitaka Kagawa ◽  
Wataru Koshibae ◽  
...  
Keyword(s):  
Electron Transport ◽  
Hall Effect ◽  
Solid Angle ◽  
Oxide Interface ◽  
High Quality ◽  
Dm Interaction ◽  
Promising Tool ◽  
Topological Hall Effect ◽  
Magnetic Skyrmions ◽  
Epitaxial Oxide

Electron transport coupled with magnetism has attracted attention over the years. Among them, recently discovered is topological Hall effect (THE), originating from scalar spin chirality, that is, the solid angle subtended by the spins. THE is found to be a promising tool for probing the Dzyaloshinskii-Moriya (DM) interaction and consequent magnetic skyrmions. This interaction arises from broken inversion symmetry and hence can be artificially introduced at interface; this concept is lately verified in metal multilayers. However, there are few attempts to investigate such DM interaction at interface through electron transport. We clarified how the transport properties couple with interface DM interaction by fabricating the epitaxial oxide interface. We observed THE in epitaxial bilayers consisting of ferromagnetic SrRuO3 and paramagnetic SrIrO3 over a wide region of both temperature and magnetic field. The magnitude of THE rapidly decreases with the thickness of SrRuO3, suggesting that the interface DM interaction plays a significant role. Such interaction is expected to realize a 10-nm-sized Néel-type magnetic skyrmion. The present results established that the high-quality oxide interface enables us to tune the effective DM interaction; this can be a step toward future topological electronics.

scholarly journals THE SPIN–ORBIT INTERACTION AND THE SPIN–SPIN INTERACTION OF PHOTONS IN AN INHOMOGENEOUS MEDIUM

2013 ◽  
Vol 27 (24) ◽  
pp. 1350172
Author(s):  
HEHE LI ◽  
ZHIGANG BU ◽  
YUEE LUO ◽  
WENBO CHEN ◽  
PEIYONG JI
Keyword(s):  
Hall Effect ◽  
Inhomogeneous Medium ◽  
Polarized Light ◽  
Orbit Interaction ◽  
Spin Interaction ◽  
Spin Orbit ◽  
Spin Orbit Interaction ◽  
Small Deflection ◽  
Transverse Deflection ◽  
Optical Metric

By means of the optical metric, we investigate the propagation of a polarized light in an inhomogeneous medium in this paper. We find that the evolution of photons is affected by the spin–spin interaction of photons, besides the spin–orbit interaction. Due to the spin–spin interaction, there is a small deflection of the ray trajectory of the polarized light along the direction of the inhomogeneity gradient of the medium. It is different from the transverse deflection described by the spin Hall effect of photons.

scholarly journals Designing zero-dimensional dimer-type all-inorganic perovskites for ultra-fast switching memory

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Youngjun Park ◽  
Seong Hun Kim ◽  
Donghwa Lee ◽  
Jang-Sik Lee
Keyword(s):  
High Throughput Screening ◽  
Stable Operation ◽  
Switching Speed ◽  
Storage Devices ◽  
Fast Switching ◽  
Halide Perovskites ◽  
And Migration ◽  
Memory Applications ◽  
Switching Memory ◽  
Fast Switching Speed

AbstractResistive switching memory that uses halide perovskites (HP) has been considered as next-generation storage devices due to low operation voltage and high on/off ratio. However, the memory still faces challenges for stable operation with fast switching speed, which hinders the practical application. Thus, it should be considered from the stage of designing the HP for memory applications. Here, we design the perovskite memory using a high-throughput screening based on first-principles calculations. Total 696 compositions in four different crystal structures are investigated and essential parameters including stability, vacancy formation, and migration are considered as the descriptor. We select dimer-Cs3Sb2I9 as an optimal HP for memory; the device that uses dimer-Cs3Sb2I9 has ultra-fast switching speed (~20 ns) compared to the device that uses layer-Cs3Sb2I9 (>100 ns). The use of lead-free perovskite avoids environmental problems caused by lead in perovskite. These results demonstrate the feasibility to design the memory with ultra-fast switching speed.

scholarly journals Switching of Skyrmion chirality by local heating

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yoshinobu Nakatani ◽  
Keisuke Yamada ◽  
Atsufumi Hirohata
Keyword(s):  
Thin Films ◽  
Building Block ◽  
Domain Walls ◽  
Local Heating ◽  
Magnetic Moments ◽  
Electrical Current ◽  
Magnetic Thin Films ◽  
Fundamental Building Block ◽  
Magnetic Skyrmions ◽  
Memory Applications

Abstract Magnetic Skyrmions are energetically stable entities formed in a ferromagnet with a diameter of typically below 100 nm and are easily displaceable using an electrical current of 102 A/cm2, resulting the Skyrmions to be more advantageous than domain walls for spintronic memory applications. Here, we demonstrated switching of a chirality of magnetic Skyrmions formed in magnetic thin films by introducing a pulsed heat spot using micromagnetic simulation. Skyrmions are found to expand with a pulsed heat spot, which induces the magnetic moments surrounding the Skyrmion to rotate by this expansion, followed by the chirality switching of the Skyrmion. Such simple controllability can be used as a fundamental building block for memory and logic devices using the chirality of Skyrmions as a data bit.

scholarly journals Ratchet baryogenesis and an analogy with the forced pendulum

2018 ◽  
Vol 33 (17) ◽  
pp. 1850097
Author(s):  
Kazuharu Bamba ◽  
Neil D. Barrie ◽  
Akio Sugamoto ◽  
Tatsu Takeuchi ◽  
Kimiko Yamashita
Keyword(s):  
Molecular Motors ◽  
Driving Force ◽  
Baryon Number ◽  
Number Density ◽  
Directed Motion ◽  
Complex Scalar ◽  
Ratchet Mechanism ◽  
Complex Scalar Field ◽  
Forced Pendulum

A new scenario of baryogenesis via the ratchet mechanism is proposed based on an analogy with the forced pendulum. The oscillation of the inflaton field during the reheating epoch after inflation plays the role of the driving force, while the phase [Formula: see text] of a scalar baryon field (a complex scalar field with baryon number) plays the role of the angle of the pendulum. When the inflaton is coupled to the scalar baryon, the behavior of the phase [Formula: see text] can be analogous to that of the angle of the forced pendulum. If the oscillation of the driving force is adjusted to the pendulum’s motion, a directed rotation of the pendulum is obtained with a nonvanishing value of [Formula: see text], which models successful baryogenesis since [Formula: see text] is proportional to the baryon number density. Similar ratchet models which lead to directed motion have been used in the study of molecular motors in biology. There, the driving force is supplied by chemical reactions, while in our scenario this role is played by the inflaton during the reheating epoch.

scholarly journals Emergence of the topological Hall effect in a tetragonal compensated ferrimagnet Mn2.3Pd0.7Ga

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Won-Young Choi ◽  
Woosuk Yoo ◽  
Myung-Hwa Jung
Keyword(s):  
Hall Effect ◽  
Magnetic Phase Diagram ◽  
Entropy Change ◽  
Spin Reorientation ◽  
Magnetic Structures ◽  
Spintronic Devices ◽  
Magnetic Compensation ◽  
Topological Hall Effect ◽  
Magnetic Skyrmions ◽  
Spin Texture

AbstractTopological spin textures such as magnetic skyrmions have attracted considerable interest due to their potential application in spintronic devices. However, there still remain several challenges to overcome before their practical application, for instance, achieving high scalability and thermal stability. Recent experiments have proposed a new class of skyrmion materials in the Heusler family, Mn1.4Pt0.9Pd0.1Sn and Mn2Rh0.95Ir0.05Sn, which possess noncollinear magnetic structures. Motivated by these experimental results, we suggest another Heusler compound hosted by Mn3Ga to overcome the above limitations. We fabricate Mn3-xPdxGa thin films, focusing on the magnetic compensation point. In Mn2.3Pd0.7Ga, we find a spin-reorientation transition around TSR = 320 K. Below the TSR, we observe the topological Hall effect and a positive magnetic entropy change, which are the hallmarks of a chiral noncollinear spin texture. By integrating all the data, we determine the magnetic phase diagram, displaying a wide chiral noncollinear spin phase even at room temperature. We believe that this compensated ferrimagnet shows promise for opening a new avenue toward chiral spin-based, high-density, and low-power devices.

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